2.13" Passive NFC-Powered e-Paper, Red / Yellow / Black / White 4-color Displaying, No Battery, Wireless Powering & Data Transfer, High Quality ABS Case. Adopts novel passive NFC technology, No battery required, no more battery life trouble. Wireless NFC-Powered Display Refreshing: Passive NFC solution, No Battery Required, No messy wiring. How it works: Wireless Powering & Data Transfer, To refresh the display content, use a smart phone with NFC function, or an NFC reader, close to the e-Paper, it'll be done in a few seconds. Note: Only Support Android phones. Specifications: Power supply: NFC Wireless Grey scale: 2 Display color: Red / Yellow / Black / White Refresh time: 16s (data transfer time is not included) Dot pitch: 0.1943 x 0.1942 (mm) Viewing angle: >170° Resolution: 250 x 122 pixels Color: White Material: ABS Package Contents: 1* 2.13inch NFC-Powered e-Paper